title: Substrate specificity of the Ogg1 protein of Saccharomyces cerevisiae: excision of guanine lesions produced in DNA by ionizing radiation- or hydrogen peroxide/metal ion-generated free radicals.
abstract: We have investigated the substrate specificity of the Ogg1 protein of Saccharomyces cerevisiae (yOgg1 protein) for excision of modified DNA bases from oxidatively damaged DNA substrates using gas chromatography/isotope dilution mass spectrometry. Four DNA substrates prepared by treatment with H2O2/Fe(III)-EDTA/ascorbic acid, H2O2/Cu(II) and gamma-irradiation under N2O or air were used. The results showed that 8-hydroxyguanine (8-OH-Gua) and 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua) were efficiently excised from DNA exposed to ionizing radiation in the presence of N2O or air. On the other hand, 8-OH-Gua and FapyGua were not excised from H2O2/Fe(III)-EDTA/ascorbic acid-treated and H2O2/Cu(II)-treated DNA respectively. Fourteen other lesions, including the adenine lesions 8-hydroxyadenine and 4,6-diamino-5-formamidopyrimidine, were not excised from any of the DNA substrates. Kinetics of excision significantly depended on the nature of the damaged DNA substrates. The findings suggest that, in addition to 8-OH-Gua, FapyGua may also be a primary substrate of yOgg1 in cells. The results also show significant differences between the substrate specificities of yOgg1 protein and its functional analog Fpg protein in Escherichia coli.
authors.affiliation: Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
authors.forename: B
authors.initials: B
authors.lastname: Karahalil
authors.forename: P M
authors.initials: PM
authors.lastname: Girard
authors.forename: S
authors.initials: S
authors.lastname: Boiteux
authors.forename: M
authors.initials: M
authors.lastname: Dizdaroglu
mesh_terms: D004249:DNA Damage; D004260:DNA Repair; D004271:DNA, Fungal / Q000378:metabolism / Q000528:radiation effects; D043382:DNA-Formamidopyrimidine Glycosylase; D029968:Escherichia coli Proteins; D005609:Free Radicals / Q000494:pharmacology; D008401:Gas Chromatography-Mass Spectrometry; D006147:Guanine / Q000031:analogs & derivatives / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism*; D011743:Pyrimidines / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity
chemical_list: D004271:DNA, Fungal; D029968:Escherichia coli Proteins; D005609:Free Radicals; D011743:Pyrimidines; D011994:Recombinant Proteins; C071023:2,6-diamino-4-hydroxy-5-formamidopyrimidine; C024829:8-hydroxyguanine; D006147:Guanine; D006861:Hydrogen Peroxide; D009699:N-Glycosyl Hydrolases; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli